。
The bill probably won't pass in the first place.
Literal
Bill [topic-は] first-of-all pass-[passive-可決される]-[negative-ない] probably
まず is an adverb meaning 'first, in the first place' — here used idiomatically with a negative verb to mean 'probably not, almost certainly not'. 可決する = 'to pass, approve (a bill)'; the passive 可決される = 'to be passed'. だろう marks a tentative prediction.